Embodiments of the present invention relate to a device and a method for stopping an etching process and, in particular, to increasing selectivity so that an etching process can be stopped securely.
Etching processes, in particular for thick layers comprising high non-uniformity as, for example, a variable layer thickness, usually require a very long over-etching process. In order to ensure secure stopping on a stop layer, often selectivities of more than 40:1 with regard to used materials of the layers to be etched and a stop layer are necessary. Both in front-end-of-line (FEOL) and also in back-end-of-line (BEOL) processes, this is difficult to realize and often additional problems make controlling the etching processes more difficult that arise as a consequence of high contamination.